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New Steel Roof on old hull


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I have a 63ft narrowboat with approximately 50foot of superstructure all in wood.

 

Obviously, otherwise why would I be here, this needs repairs and replacement...

 

Looking through all the comments available with Google search most say don't repair, replace with steel it'll be cheaper.

I'll be honest I would replace if I could afford it however I can't. At least I assume I can't.

I was hoping to find some guide prices however haven't really done so. 

If anyone could help here with rough estimates and recommendations of boatyards who can and will do this I would be grateful.

I'm on the Kennet and Avon.

 

Otherwise it is going to have to be a repair and replace with epoxied marine ply.

 

Many thanks

 

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Overskin the cabin as it is with steel, seen it done in a weekend. So you keep all your interior intact.

Seem to remember that a boat builder in Southam Oxfordshire did one for an old friend some time back

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Hi Tracy, Thanks for the fast response!

 

Do you remember if this was a welded construction or was it steel panels screwed to the existing structure?

I suspect if it was Southam it may have been Kedian Engineering?

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If you completely replace the wooden cabin with a new steel cabin a substantial part of the work will be the stripping out of the existing and refitting of the new.  If your fitout is generally in good condition I would go with Tracy's suggestion.

 

I think the Southam boatbuilder mentioned is Martin Kedian of www.kedianengineering.co.uk.

 

4 minutes ago, RS_Pete said:

 

Do you remember if this was a welded construction or was it steel panels screwed to the existing structure?

There's a few been done with fully welded seams, and no screws penetrating the new watertight skin. No framing - relies on the timber structure inside for support.

Edited by David Mack
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4 minutes ago, RS_Pete said:

Hi Tracy, Thanks for the fast response!

 

Do you remember if this was a welded construction or was it steel panels screwed to the existing structure?

I suspect if it was Southam it may have been Kedian Engineering?

That's the guy of course, Martin.  

The cabin was all welded, the existing windows refitted I think.  Front and back bulkheads all fitted with doors and hatches. It looked like any other steel top when done.

I think Martin has automated welders which makes welding cabin sides a lot easier and quicker.

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1 minute ago, David Mack said:

If you completely replace the wooden cabin with a new steel cabin a substantial part of the work will be the stripping out of the existing and refitting of the new.  If your fitout is generally in good condition I would go with Tracy's suggestion.

 

I think the Sotham boatbuikder mentioned is Martin Kedian of kedianengineering.co.uk.

 

That stripout shouldn't take too long! The boat was effectively a blank canvas so fitout is effectively a little way off at the moment. Really need to decide where the rapidly diminishing budget is best spent and order of attack. My preference is for steel for the longevity and maintenance point of view, though I have to admit a perverse fondness for the wooden top...

1 minute ago, Tracy D'arth said:

That's the guy of course, Martin.  

The cabin was all welded, the existing windows refitted I think.  Front and back bulkheads all fitted with doors and hatches. It looked like any other steel top when done.

I think Martin has automated welders which makes welding cabin sides a lot easier and quicker.

I have sent an enquiry to Martin. I expect it'll be a few days before I hear back with it being a holiday weekend however when I do will report back on here. Just have to figure out the best course of action...and route to Southam from the west end of the K&A...

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32 minutes ago, David Mack said:

If you completely replace the wooden cabin with a new steel cabin a substantial part of the work will be the stripping out of the existing and refitting of the new.  If your fitout is generally in good condition I would go with Tracy's suggestion.

 

I think the Southam boatbuilder mentioned is Martin Kedian of www.kedianengineering.co.uk.

 

There's a few been done with fully welded seams, and no screws penetrating the new watertight skin. No framing - relies on the timber structure inside for support.


Are you sure about that bit? A relatively thin gauge welded steel plate isn’t going to fit flush and tight onto a hardwood cabin structure without some form of mechanical fixing. Vulpes has a hardwood cabin structure skinned in steel by Graham Edgson - who apparently devised a standard technique for such work - and all the the cut edges of the steel skin are fixed to the super structure. There are also various attachments - such as footsteps - that by nature have to penetrate the skin. But that’s no different to any boat.

Edited by Captain Pegg
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If it wasn't for the bottom edges I wonder if that stuff that lorry trailer sides are made of (No, not curtainsiders!) would be the answer to old wooden tops. Mind you I suppose putting a 40` length on the car roof to bring it home could be awkward. Somebody must have done it.

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Well I have had a reply from Martin.

Unfortunately due to Covid and its restrictions he needs to focus on his current business orders and is unable to help with this.

 

I suspect his will not be the only boatyard in this position at present so it may be the repair option is the only option.....

(Of course there's always that cheap welder and some tinsnips on FB marketplace....?)

1 minute ago, Bee said:

If it wasn't for the bottom edges I wonder if that stuff that lorry trailer sides are made of (No, not curtainsiders!) would be the answer to old wooden tops. Mind you I suppose putting a 40` length on the car roof to bring it home could be awkward. Somebody must have done it.

Hmmm....3 sheets approx 1.5 metres by 15 metres on the BMW might prove interesting....

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1 minute ago, RS_Pete said:

Well I have had a reply from Martin.

Unfortunately due to Covid and its restrictions he needs to focus on his current business orders and is unable to help with this.

 

I suspect his will not be the only boatyard in this position at present so it may be the repair option is the only option.....

(Of course there's always that cheap welder and some tinsnips on FB marketplace....?)

True but 800 feet of welding is a daunting task!

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I think if I was re-skinning a wooden top I might use aluminium sheet, PU sealant and screws rather than steel. Lighter and less likely to affect stability than steel and easier to DIY. Plus it's corrosion free so if you liked the look no need to paint it, or paint with an etch primer and nobody will know it's not steel.

Edited by blackrose
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5 minutes ago, blackrose said:

I think if I was re-skinning a wooden top I might use aluminium sheet, PU sealant and screws rather than steel. Lighter and less likely to affect stability than steel and easier to DIY. Plus it's corrosion free so if you liked the look no need to paint it, or paint with an etch primer and nobody will know it's not steel.

The current top appears to have this done, at least in part. The existing construction, which is 18mm plywood has been repaired previously and is faced with sheet metal and then covered in a cloth painted with a bitumen paint (and yes that looks as bad as it sounds…), is somewhat sad and tired with sections needing replacing.

Unfortunately I have no idea when it was done and it may have been applied over existing damaged wood, or has actually trapped moisture in as the current panelling is pretty rotten in places.

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Part of the problem I have is, I think, caused by the previous owners attempts to protect the roof actually acting as a catchtank for water trapping it under poorly fitted tarps.

Properly fitted as that centre section appears to be in the photo on Bargus may be the way forward while repairs are ongoing. 

Looks like replacement of outer panels and any other rotten wood with marine ply sealed with two pack epoxy will be the starting point. 

Fingers crossed 

 

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13 hours ago, RS_Pete said:

Part of the problem I have is, I think, caused by the previous owners attempts to protect the roof actually acting as a catchtank for water trapping it under poorly fitted tarps.

 

 

 

Yes anything that's put over the top must be properly sealed otherwise it's just going to trap water and make matters even worse.

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Hard to know without actually poking around with a sharp thing. Many boats were made with pine floorboards or similar screwed to 3" x "2 framing and then clad with ply or oil tempered hardboard - all just an example. These are repairable by just taking off the outer skin, replacing any rotten bits and re skinning with something better or rotproof. Aluminium would be good, even perspex or plastic sheet of some sort would be good, whatever is not hugely expensive. Might need some cheap board under it to give some insulation to the thing. As ever its the edges that are going to be a problem.

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1 hour ago, David Mack said:

And that is going to be hard with a solution with numerous screw holes and long lengths of sealed seams.

Indeed.

And truthfully I don't see an easy or economic option open to me.

At least with a "repair and make good" option it can be done piecemeal... unlike a steel top which will be done all at once as a one off but at unknown cost.. assuming there is anyone out there willing to do it. 

I have the skill sets to do either myself, though experienced guidance is always a bonus. I just lack facilities and £££'s currently. So it looks like timber/ ply replacement and repairs.

 

All advice most welcome though?

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59 minutes ago, Bee said:

Hard to know without actually poking around with a sharp thing. Many boats were made with pine floorboards or similar screwed to 3" x "2 framing and then clad with ply or oil tempered hardboard - all just an example. These are repairable by just taking off the outer skin, replacing any rotten bits and re skinning with something better or rotproof. Aluminium would be good, even perspex or plastic sheet of some sort would be good, whatever is not hugely expensive. Might need some cheap board under it to give some insulation to the thing. As ever its the edges that are going to be a problem.

Oh I've been poking with a sharp thing.....?I have stripped the inner cladding back to gain access to the first 6 metres or so.

Due to the over cladding with metal on the outside access is difficult there though the cladding doesn't appear to have been the full length and is only on the vertical surfaces where applied. Definitely worse where clad though that may mean its older....

The starboard side is, oddly, in far worse condition than the port side, both appearing to be constructed at the same time using the same materials.

The roof is worse at the bow and the stern leading me to think that it has been subject to patchwork repairs before. I also don't think there is sufficient framing giving support to the roof and sides...

So I will tackle the first 5metres and then the next and then the next and presumably return to the beginning to fix anything I got wrong the first time.....

And repeat?

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1 hour ago, blackrose said:

 

Yes anything that's put over the top must be properly sealed otherwise it's just going to trap water and make matters even worse.

Yes quite, never had any problems with  the front section which is the tarp laid over ply no joins but there are numerous holes in the middle section over the cabin proper and although these were sealed when it was first put over time leakage caused localised rot, the job gave us another 8-10 years though. If the op could do the same but do away with the hand rail and vents in the roof and have some sort of seal / flashing at the bottom it could work.

 

33 minutes ago, RS_Pete said:

Oh I've been poking with a sharp thing.....?I have stripped the inner cladding back to gain access to the first 6 metres or so.

Due to the over cladding with metal on the outside access is difficult there though the cladding doesn't appear to have been the full length and is only on the vertical surfaces where applied. Definitely worse where clad though that may mean its older....

The starboard side is, oddly, in far worse condition than the port side, both appearing to be constructed at the same time using the same materials.

The roof is worse at the bow and the stern leading me to think that it has been subject to patchwork repairs before. I also don't think there is sufficient framing giving support to the roof and sides...

So I will tackle the first 5metres and then the next and then the next and presumably return to the beginning to fix anything I got wrong the first time.....

And repeat?

It may have been rotten before the original overcladding. Long term the best solution is a new steel top but if short of cash like we were you can keep a wooden structure going for some time just be aware that you are adding nothing to the boat's value and will be constantly redoing stuff. Do keep an eye out for dry rot thats the killer, wet rot in small areas can just be cut away and made good before covering with whatever you decide to weatherproof it. One benefit of the canvas is that there may be a certain amount of ventilation under it as the wind lifts it., As for the frames if it is too hard to cut away and replace like for like you can possibly add extra frames or bolt new timbe to the existing frame to reinforce it, may look ugly but needs must. Do use pretreated timber!

41 minutes ago, RS_Pete said:

And repeat?

undoubtedly

 

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2 hours ago, David Mack said:

And that is going to be hard with a solution with numerous screw holes and long lengths of sealed seams.

 

If you minimise mechanical fixings and use a good sealant it shouldn't be that hard. Bonding sheet materials with large surface areas using modern PU construction adhesives/sealants you shouldn't need lots of screws. Do some bonding tests if you want with Stixall from Toolstation. Key the underside of the aluminum with a medium grit paper and clean both surfaces with a bit of white spirit on a cloth. You'll be surprised how strong the bond is after 24 hours.

Edited by blackrose
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I have had three nb's with wooden tops one of which I built and I currently still have. All of them have had some plywood content which is where the problems generally occur first. The problem with all wooden tops is that your have to accept they require almost continuous maintenance and that what appears to be a small amount of rot, when it dries out is considerably larger. Unless you can completely remove the rotten wood and dry it out completely any covering such as GRP  is likely to increase the rate of decay. I guess your main concern is damp and leaks unless a high quality appearance is important. It is very difficult to get decent quality timber and wood these days and when you find it very expensive so if you want a long term future  steel is probably the best way to go. I don't know the boat but assuming it is a modern parallel hull with an upstand on the inner side of the gunnel one option might be to get some sections of cabin say 10ft long made by a steel fabricator and then placed into position one at a time on the boat and welded or bolted together.

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I have seen some inspired and impressive cabin work built onto a converted 1930s Joey boat using double-skinned marquee canvas - in-filled with sheets of expanded foam-board for insulation.

 

As I remember, the gunwales were sacrificed in order to attach the sheeting along the edges. At ceiling level was a wide top plank with a natural hardwood frame hanging down from it outwards at about 30-degrees, covered by a separate sheet of canvas (or translucent Monotex) the full length of the boat. The canvas walls dropped down to the gunwales from the edges of this hanging frame at an ordinary tumblehome, and were adjusted/tightened by ropes within the upper frame (nice, white, nautical looking ropes). This boater had even installed lead lined windows in wooden frames into the doubled canvas walls at various places where they were needed. All this stuff was recycled, bought inexpensively or pulled out of skips. Genius really, along with real craftmanship. But it shows what you can do with time and skills.

 

It's a good time of year to begin this sort of project.

 

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Thanks Jim, I'd love to see a picture of this if one is available.

I love some of the ingenuity that can be found out there, not just in the boating community, and often find myself disappearing down an internet rabbit hole for hours when looking at what can be done.

The small home movement have a lot to answer for!

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